Shrinkproofing wool with oxidizing agents using foulard liquid application technique

ABSTRACT

Shrinkproofing of continuous lengths of wool is effected by wetting out with an aqueous solution containing predetermined amounts of a wetting agent and two oxidizing agents for wool which react therewith at substantially different rates, immediately passing the wetted out wool through a precision nip and then allowing the thus-predetermined amount of solution to remain in contact with the wool while the desired oxidation takes place. The solution containing the two oxidizing agents is an unstable one and is freshly prepared from stable solutions as it is used up. The rate of admixture of the stable solutions is correlated with the rate of pickup of liquor by the wool so that the volume of prepared treating liquor remains constant and complete renewal thereof takes place in 1 to 15 minutes.

United States Patent I I 1 I I I I Continuation of application Ser. No. 453,369, May 5, I965, now abandoned. This application Apr. 30, I970, Ser. No. 31,831

SI-IRINKPROOFING WOOL WITH OXIDIZING AGENTS USING FOULARD LIQUID APPLICATION TECHNIQUE 8 Claims, 1 Drawing Fig.

US. Cl 8/l27.6, 8/128 Int. Cl ..I)06m 03/08, D06m 3/I2, D06m 13/38 Field of Search 68/22 B; 8/l27.6, I28

Primary Examiner-George F. Lesmes Assistant Examiner.l Cannon Au0rneyWenderoth, Lind & Ponack ABSTRACT: Shrinkproofing of continuous lengths of wool is effected by wetting out with an aqueous solution containing predetermined amounts of a wetting agent and two oxidizing agents for wool which react therewith at substantially different rates, immediately passing the wetted out wool through a precision nip and then allowing the thus-predetermined amount of solution to remain in contact with the wool while the desired oxidation takes place. The solution containing the two oxidizing agents is an unstable one and is freshly prepared from stable solutions as it is used up. The rate of admixture of the stable solutions is correlated with the rate of pickup of liquor by the wool so that the volume of prepared treating liquor remains constant and complete renewal thereof takes place in l to 15 minutes.

PATENTEU DECZI IBYI 3,628,908

PERMONOSUL PHUR/C L SOD/UM A C ID l DICHLOROC YANURA TE Ill WOOL C; AND C CONSTANT HEAD TAN/(S F7 AND F FLOWMETERS M M/xr/ve TANK R RESERVOIR B N NIP CONTAINING TREATMENT BATH To BRATT/CE SH RINKPROOFING WOOL WITH OXIDIZING AGENTS USING FOULARD LIQUID APPLICATION TECHNIQUE This is a continuation of application Ser. No. 453,369, filed May 5, I965 and now abandoned. This invention relates to improvements in the treatment of wool to impart shrink resistance thereto and is more especially concerned with the treatment of materials consisting of or containing wool which are available in continuous form, or which can readily be joined together into a continuous form to enable the same to be subjected to substantially uniform treatment.

Woollen materials which are available in continuous form include yarns, tops and woven and knitted fabrics consisting of or containing wool. Lengths which serve as a continuous form may also be formed by sewing together knitted garments such as socks: these are then separated after completion of the treatment.

Processes are known for the treatment of wool to impart shrink resistance thereto which involve the application of two distinct chemical reagents to the wool. As a rule these may be applied either simultaneously or successively. One difficulty which arises in simultaneous treatment is due to the fact that different chemical reagents almost invariably react with wool at different rates, This need not give rise to undue difficulty in batch processing, but in continuous processing difficulties arise.

It is an object of the present invention to provide an improved continuous process for imparting shrink resistance to wool in a continuous form in which the wool is simultaneously treated with a plurality of chemical reagents which react therewith at different rates.

According to the present invention there is provided a process for imparting shrink resistance to wool and wool-containing materials which comprises wetting-out a continuous form of such a material with an aqueous liquor containing (a) a wetting agent and (b) at least two shrink-resistance-imparting oxidizing agents for wool which react with woollen fibers at substantially different rates and together product a shrinkresistant effect thereon, substantially immediately after wetting-out passing the wetted-out material through the nip between a pair of rollers so as to ensure that the material is uniformly impregnated with a controlled amount of said liquor and maintaining said controlled amount of liquor in contact with said material until at least a desired amount of each of said chemical reagents has reacted with the wool with which it is in contact.

According to a feature of the invention metered quantities of aqueous solutions of each of said oxidizing agents are fed into said aqueous liquor to maintain the desired composition thereof, which quantities are correlated with the rate of pickup of liquor by woollen materials undergoing treatment so that (a) the volume of liquor remains substantially constant and (b) complete renewal of liquor takes place in I to 15 minutes.

The invention may be performed in various ways and employing various reagents.

One reagent system to which the invention is applicable is an aqueous solution containing an alkali metal permanganate, e.g., potassium permanganate and an alkali metal or calcium hypochlorite at pH values between 5 and 10. In this system the hypochlorite reacts much more readily with wool than the permanganate. Thus, much longer contact is necessary for the permanganate to react with the wool than is required for the hypochlorite to react.

Another reagent system to which the invention is applicable is an aqueous solution containing permonosulfuric acid and an alkali metal dichloroisocyanurate, e.g., sodium or potassium dichloroisocyanurate. At pH values below 5, e.g., 2.0 to 4.0 which are encountered with such systems the dichloroisocyanurate reacts with the wool at a much more rapid rate than the permonosulphuric acid. The use of the dichloroisocyanurate at the indicated pH values has, moreover, the advantage that the characteristic yellowing of wool associated with its use at higher pH values is avoided.

Other reagent systems to which the invention is applicable are (a) an aqueous solution containing permonosulfuric acid and sodium or potassium hypochlorite and (b) the system con taining peracetic acid and sodium or potassium hypochlorite.

The passage of a continuous form of wool through a large volume immersion bath containing one of the above systems is attended by unpredictable results. The first portion of the wool undergoing treatment will be vigorously attacked by the more rapidly reacting reagent and subsequent portions will be less severely attacked as the concentration decreases. The change in the concentration of the slower acting reagent will be more gradual. However, it is clear that the shrink-resistance imparted to the wool by such a bath in continuous use will be quite unpredictable. While it is theoretically possible to maintain the concentrations of the reagents at desired values, this, in practice, has not proved feasible in a system of this kind.

The present invention seeks to overcome difficulties of the kind outlined above by supplying to each increment of material a controlled amount of treating liquor containing regulated amounts of each of the reagents and maintaining this controlled amount of liquor in contact with that increment of material until a predetermined proportion, or the whole, of each of the reagents has reacted therewith. In this way a much more closely controlled shrink resistance can be applied in continuous operation than has hitherto been possible with such systems.

In carrying out the process of the present invention reservoirs containing aqueous solutions of each of the two reagents are first prepared. Either or both of these solutions may also contain a wetting agent. While any kind of wetting agent may be used an anionic or a nonionic wetting agent is preferred. These two solutions in metered quantities are admixed only shortly prior to application to the woollen material undergoing treatment.

In one form ofthe invention the woollen material is supplied with a controlled amount of treating liquor by passage through a bath of small capacity which receives liquor from the reservoirs referred to above. The wetted-out material is then sub stantially immediately passed between the nip of a pair of precision rollers located adjoining the exit from the bath. The nip at the rollers is so adjusted as to ensure that the woollen material passing therethrough retains within its interstices a volume of treating liquor containing an amount of the treating reagents which is sufiicient to impart to the material a predetermined shrink resistance within a given time. After passing through the precision nip the liquor-containing goods are run forward over and under rollers or on a brattice or scray or otherwise retained in contact with the liquor 'for a time sufficient to allow the whole of both reagents, or at least a predetermined proportion of each which will suffice to impart the desired degree of shrink resistance, to react. The pickup of aqueous liquor at the nip may be 50-250 percent of the weight of the wool; the preferred pickup is -150 percent.

It should be noted that the time of residence or immersion in the bath is substantially only sufficient to ensure that the goods are fully wetted out by the aqueous liquor in the bath. A preferred time for residence or immersion of the wool in the bath is 1 to 2 seconds. This is sufficient time to ensure thorough penetration and wetting-out of the wool but is insufficient to allow any significant exhaustion of the liquor in the bath. The concentration of the liquor remains at virtually the same concentration as that of the liquor fed into the bath. A bath having a capacity of l to 2 gallons of liquid is contem plated although smaller and somewhat larger baths may be used if the circumstances, such as the rate of removal of liquor from the bath, require. It is a feature of the invention that the volume of liquid admitted to the bath is correlated with the rate of pickup of liquor by the woollen materials passing through the bath so that complete renewal of the bath liquor takes place in a period of l to 15 minutes: preferably the time for complete renewal is less than 10 minutes. These times of renewal are insufficient for appreciable decomposition of the oxidizing agents to occur before coming into contact with the woollen material. Thus, the material as it passes through the bath takes up a controlled amount of virtually fresh, uncontaminated liquor. There is virtually no opportunity for an extraneous substances present in the woollen materials, such as combing oils present in tops, to pass from the materials into the bath and thus accumulate therein. In consequence it is possible to produce a much more closely standardized treated wool having a predictable degree of shrink resistance imparted thereto. Moreover, any adventitious salt present in the contents of either reservoir is carried forward in the interstices of the materials and thus remains a substantially constant factor ifit has any influence at all upon the shrink resistance reactions.

It has already been observed that the volume of liquid admitted to the bath is correlated with the rate of pickup of liquor by the materials passing therethrough. Initially the bath is filled to the desired extent with liquor of the desired com position. The volume of liquor in the bath is then maintained substantially constant throughout substantially the whole of the, run by metering fresh solution from each of the reservoirs of oxidizing agent into the bath in such proportions as to main tain the composition of the bath substantially constant. Only during the last few minutes of a run should the volume of liquor in the bath be allowed to fall.

1n an alternative form of the invention the woollen material is supplied with a controlled amount of treating liquor by substantially uniformly spraying liquor from a tank on to both sides of the material. The spraying may be done from a manifold located upon each side of the goods. The tank receives liquor from the reservoirs referred to above and devices are provided for replenishing the contents of the tank from the reservoirs as the liquor is used. Accurate adjustment and uniform distribution of the pickup is secured by passing the sprayed material between the nip of a pair of rollers in the manner already indicated.

Considering in more detail, as an example of the process. the permonosulfuric acid-alkali metal dichloroisocyanurate system, two reservoirs are used, one of which contains an aqueous solution of permonosulfuric acid and preferably a wetting agent, while the other contains sodium or potassium dichloroisocyanurate. The permonosulphuric acid solution may have a pH value of 1.0 to 2.0, while that of the dichloroisocyanurate solution is approximately 5, at which pH, value it is stable. When the solutions are mixed the resulting solution has a pH value of about 3, and the dichloroisocyanurate is no longer stable. By mixing the solutions as they are required for impregnation the resulting system does not have time to undergo appreciable decomposition before it is applied to woollen material undergoing treatment since the bath or tank should not contain more liquor than is expected to be used in the ensuing one to minutes. This mixed solution is rapidly picked up in a measured dose by wool using the above described techniques and then reacts completely or virtually completely with the wool during a dwell period before further processing. At the conclusion of the treatment any residual treating agents and reaction products derived therefrom are removed by washing the treated material with water. The wool is then passed through a dilute aqueous solu tion of a reducing agent such as sodium sulphite or sodium bisulphite in order to complete the shrink-resist treatment. The thus treated material is then again washed with water and finally dried.

In the case of the permonosulfuric acid and alkali metal hypochlorite system two reservoirs are used, one of which contains an aqueous solution of permonosulfuric acid and preferably a wetting agent, whilst the other contains sodium or potassium hypochlorite. The permonosulfuric acid or potassium hydrogen permonosulfate solution which may contain added sulfuric acid, may have a pH value of 0.5 to 2.0, while that ofthe hypochlorite solution is approximately 8.0 to 9.0 at which pH value it is stable. When the solutions are mixed the resulting solution has a pH value of about 3 to 5, according to the ratio in which the solutions are mixed, and the hypochlorite is no longer completely stable. By mixing solutions as they are required for impregnation the resulting system does not have time to undergo appreciable decomposh tion before it is applied to the woollen material undergoing treatment. The preferred pH value of the bath is 3.5 to 4.5.

The following examples illustrate the nature of the invention.

EXAMPLE 1 Ten continuous lengths of wool tops, each weighing 20 g. per meter. are passed through a bath having a capacity of 4.5 liters and filled with a solution containing 1.77 percent by weight of potassium hydrogen permonosulfate (which is equivalent in oxidizing power to 1.33 percent permonosulfuric acid), 0.5 percent by weight of Tergitol TMN (a nonionic wetting agent) and 1.33 percent by weight of sodium dichloroisocyanurate; this solution has a pH value of substantially 3. After passing through the solution the wool enters a precision nip adjusted so that the pickup of solution is percent of the weight of the wool. The speed of the wool is 5 meters per minute. Thus 1 kg. of wool passes through the bath and nip each minute, taking away with it 1.5 liters ofthe above treating solution.

The bath is kept full by metering into it a liquor obtained by admixing (i) 750 cc. per minute of 3.54 percent by weight aqueous solution of potassium hydrogen permonosulphate containing 1 percent by weight of Tergitol TMN and having a pH value of l, and (ii) 750 cc. per minute of 2.66 percent by weight aqueous solution of sodium dichloroisocyanurate having a pH value of 6. These two solutions are stable for long periods and they are only admixed immediately prior to use.

Since the bath has a capacity of4.5 liters and the mixture is used up at the rate of 1.5 liters per minutes, the mixture remains in the bath for a period of 3 minutes. During this 3 minutes the loss in oxidizing power is negligible. The dwell time ofthe wool in the bath is 1.5 to 2.0 seconds.

After passing the precision nip the wool is allowed to fall upon a brattic moving at such a speed that the wool remains thereon for 1.5 to 2.0 minutes and then passes through the following baths: (a) rinse bath of water, (b) aqueous 5 percent sodium sulphite solution at pH 7.2 and (c) two further rinse baths of water. The dwell time in the sodium sulphite bath is 30 seconds. The material is then dried.

Samples of treated and untreated wool tops were submitted to a standard washing test in the Dylan Cubex Machine with the following results: Untreated control 21 percent shrinkage; treated material 2 percent shrinkage.

EXAMPLE 2 Woven and knitted wollen fabrics are treated in the equipment described in example 1 using a solution containing 1.33 percent by weight of potassium permanganate, 1 percent by weight of Tergitol TMN, sodium hypochlorite to provide 1.33 percent by weight of available chlorine and 5 percent by weight of magnesium sulfate. The pH value of the solution was 9.3.The rate of passage of the fabric through the bath is 1 kg. per minute and the precision nip is set so that the pickup of solution is 150 percent of the weight of the wool. The treat ment is thus with 2 percent of the weight ofthe wool of potassium permanganate and 2 percent of available chlorine.

The bath is kept full by metering into it a liquor obtained by admixing (i) 750 cc. per minute of a solution containing 2.66 percent by weight aqueous solution of potassium permanganate and sodium hypochlorite in an amount which yields 2.66 percent of available chlorine, and (ii) 750 ccs. per minute of a 10 percent by weight aqueous magnesium sulphate containing 2 percent by weight of Tergitol TMN. This involves complete replacement of the bath every 3 minutes.

The wool immediately assumes a dark brown color due to deposition of manganese dioxide. It is allowed to fall on a moving brattice where it remains for 2 minutes, after which time the reaction is substantially complete. The treated wool then passes through the following baths: (a) rinse bath of water, (b) 3 percent by weight aqueous sodium bisulphite solution containing 1 percent of formic acid, and (c) two further rinse baths of water. The dwell time in the sodium bisulphite bath is 25 to 30 seconds. The material is then dried at 80 C.

Samples of treated and untreated fabric were submitted to a standard washing test in the Dylan Cubex Machine with the following results: Untreated control 28 percent shrinkage; treated material 5 percent shrinkage.

EXAMPLE 3 Example 2 was repeated but the concentration of the potassium permanganate-sodium hypochlorite solution was increased so that the wool was treated with 3 percent of its weight of potassium permanganate and 3 percent of available chlorine. When submitted to the standard washing test the treated material showed 2 percent shrinkage.

EXAMPLE 4 Wool is continuously treated in the same manner as described in example 2 with the modification that the bath is kept full by metering into it a liquor obtained by admixing (i) 750 cos/min. ofa solution containing 2.6 percent by weight of an aqueous solution of potassium permanganate and sodium hypochlorite in an amount which yields 2.66 percent of available chlorine and (ii) 750 cos/min. of a percent by weight aqueous solution of magnesium sulphate containing 2 percent by weight of Tergitol TMN and a quantity of sulfuric acid such that when (i) and (ii) are mixed in equal amounts the pH of the thus produced solution is 7.0.

The treated wool when submitted to the standard washing test shows a shrinkage of 2 percent.

The invention is further illustrated in the accompanying drawing which is a flow sheet illustrating the use of aqueous solutions of the two oxidizing agents permonosulfuric acid and sodium dichloroisocyanurate. A constant head of aqueous permonosulfuric acid solution is maintained in a constant head tank C, whence it flows along an outlet line L in which is inserted a flowmeter F The flowmeter F controls the amount of permonosulfuric acid solution flowing along line L,. A constant head of aqueous sodium dichloroisocyanurate solution is maintained in constant head tank C whence it flows along an outlet line L in which is inserted a flowmeter F The flowmeter F controls the amount of isocyanurate solution flowing along line L The controlled quantities of permonosulfuric acid solution passing flowmeter F, and of sodium dichloroisocyanurate passing flowmeter F are delivered into a mixing tank M which is provided with a suitable stirrer to ensure adequate mixing. Tank M is provided with an overflow line L When tank M is full to the overflow level the volume of liquid passing along line L is equal to the sum of the volumes of liquid passing flowmeter F, and F The overflowing liquid from tank M falls into a small reservoir R provided with an outlet line L along which mixed liquid passes to the treating bath B which is located between a pair of rollers rotating in the directions shown. Bath B is provided with suitable liquidtight ends. A continuous form of wool travelling from left to right passes over a roller and then vertically downwards into bath B and through an adjustable nip between the rollers generally designated N. This nip determines the pickup of liquid by the wool from the bath B. After passing the nip the wool impregnated with a treating solution of the two oxidizing agents passes round a further roller and then resumes its left to right travel on its way to a brattice or scray, not shown in the drawing on which it remains for a time sufficient to ensure that the desired degree of oxidation of the wool takes place.

Flowmeters F and F are, in practice, set to deliver a total volume of liquid equal to the pickup at the nip N.

We claim:

I. A process for imparting shrink-resistance to wool and wool-containing materials which comprises wetting out continuous lengths of said material by immersing said material in a bath of an aqueous liquor containing (a) a wetting agent, and (b) two shrink-resistanceimparting oxidizing agents for wool which react with woolen fibers at substantially different rates and which together produce a shrink-resistant effect thereon; the residence time in said bath being sufficient to insure thorough penetration and wetting out of the wool but insufficient to allow any significant exhaustion of the liquor in the bath,

B. immediately after wetting out passing the wetted out material through the nip between a pair of rollers so as to ensure that the material is uniformly impregnated with a controlled amount of said liquor,

C. maintaining said controlled amount of liquor in contact with said material until at least a desired amount of each of said oxidizing agents has reacted with the wool with which it is in contact and D. metering quantities of aqueous solutions containing each of said oxidizing agents and said wetting agent into said aqueous liquor so as to maintain the composition thereof substantially constant, said metered quantities being correlated with the rate of pickup of liquor by woolen materials undergoing treatment so that the volume of said aqueous liquor remains substantially constant, and so that complete renewal of said liquor takes place in from I to 15 minutes.

2. A process according to claim 1 in which complete renewal of liquor takes place within 1 to 10 minutes.

3. A process according to claim 1 in which the time of immersion of said materials in said bath is 1 to 2 seconds.

4. A process according to claim 1 in which the pickup of liquor at the nip between said rollers is to I50 percent of the weight of the woolen material.

5. A process according to claim 1 in which one oxidizing agent is permonosulphuric acid and the other is an alkali metal dichloroisocyanurate and the pH of the liquor is below 5.

6. A process according to claim 1 in which one oxidizing agent is permonosulfuric acid and the other is an alkali metal hypochlorite and the PH of the liquor is about 3 to 5.

7. A process according to claim 1 in which one oxidizing agent is an alkali metal permanganate and the other is an alkali metal or calcium hypochlorite and the pH is between 5 and 10.

8. A process according to claim 1 in which the thus treated wool is thereafter treated with a dilute aqueous solution of a reducing agent. 

2. A process according to claim 1 in which complete renewal of liquor takes place within 1 to 10 minutes.
 3. A process according to claim 1 in which the time of immersion of said materials in said bath is 1 to 2 seconds.
 4. A process according to claim 1 in which the pickup of liquor at the nip between said rollers is 100 to 150 percent of the weight of the woolen material.
 5. A process according to claim 1 in which one oxidizing agent is permonosulphuric acid and the other is an alkali metal dichloroisocyanurate and the pH of the liquor is below
 5. 6. A process according to claim 1 in which one oxidizing agent is permonosulfuric acid and the other is an alkali metal hypochlorite and the PH of the liquor is about 3 to
 5. 7. A process according to claim 1 in which one oxidizing agent is an alkali metal permanganate and the other is an alkali metal or calcium hypochlorite and the pH is between 5 and
 10. 8. A process according to claim 1 in which the thus treated wool is thereafter treated with a dilute aqueous solution of a reducing agent. 